The Calendar hole will go live in approximately 13 days. Why not try and solve it ahead of time?
ISBN in Python in bytes. Achievements Cheevos Holes Languages Medals Miscellaneous All Holes 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig 05AB1E ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig Experimental Language 05AB1E ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Hole All 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Experimental Hole Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Bytes Time Submitted 79th TaserTheFox 🇺🇸 843 108 9ms 3 Apr 2023 79th jatloe 843 108 10ms 26 Aug 2024 79th cros107 🇦🇺 843 108 10ms 10 Aug 2025 84th ZakkkkAttackkkk 🇵🇭 835 109 10ms 23 Feb 2022 84th cefqrn 835 109 9ms 24 Dec 2022 84th AlexanderFair 835 109 10ms 11 Jul 2023 84th firegene 🇮🇪 835 109 10ms 18 Jan 2024 84th PixelSoftwareStudios 🇺🇸 835 109 10ms 6 Jul 2024 84th andrewjc2000 835 109 10ms 9 Mar 2025 90th btjones0 827 110 11ms 25 Jan 2022 90th adamnielson42 🇺🇸 827 110 9ms 25 Apr 2023 90th sultan 827 110 9ms 24 Feb 2024 90th fgrosshans 🇫🇷 827 110 10ms 16 Jul 2024 90th edsrzf 🇳🇿 827 110 9ms 30 Jul 2025 90th InigoK 🇺🇸 827 110 10ms 22 Sep 2025 90th albanian-laundromat 827 110 11ms 7 Nov 2025 90th vhoulbreque 🇫🇷 827 110 11ms 23 days ago 98th neihousaigaai 820 111 11ms 11 Jan 2022 98th knutae 🇳🇴 820 111 10ms 18 Jan 2022 98th rschwa6308 🇺🇸 820 111 9ms 22 Mar 2023 98th zbreit 🇺🇸 820 111 11ms 22 Mar 2023 98th plcc0 820 111 9ms 3 Mar 2025 98th emgordon154 820 111 10ms 25 Mar 2025 98th BREMAUCY 🇫🇷 820 111 10ms 15 Apr 2025 98th now4est 🇯🇵 820 111 9ms 25 Sep 2025 106th guilhem-roy 🇫🇷 813 112 9ms 5 Jun 2022 106th ahmetdemirag 🇨🇾 813 112 9ms 30 Jun 2024 106th CommandLeo 🇮🇹 813 112 10ms 3 Nov 2025 109th commandblockguy 🇺🇸 805 113 11ms 3 Nov 2022 109th jakobkordez 🇸🇮 805 113 9ms 13 Nov 2022 109th mossprescott 805 113 9ms 16 Jan 2023 109th SB-945 805 113 10ms 19 Aug 2023 109th davitf 805 113 9ms 30 Apr 2024 109th kbeat 🇰🇿 805 113 12ms 18 May 2025 115th aonkeeper4 798 114 9ms 5 Jul 2022 115th frankgraziano 798 114 10ms 8 Jan 2023 115th m42km 798 114 9ms 22 Nov 2023 115th thienudomsrirungruang 798 114 16ms 14 May 2024 115th jtaxen 798 114 10ms 8 Jun 2024 115th CutSandstone 798 114 9ms 8 Jul 2024 121st jmerle 🇳🇱 791 115 9ms 22 Jan 2022 121st PiterAnnema 791 115 16ms 23 Mar 2022 121st AGoyet 791 115 9ms 29 Jun 2022 121st Eilonlif 🇮🇱 791 115 10ms 11 Sep 2022 121st IsmaelGSerrano 791 115 10ms 2 Nov 2022 121st bobbysq 791 115 9ms 22 Jan 2023 121st msbranicky 791 115 9ms 25 Jul 2023 121st ArenaGrenade 791 115 10ms 19 Feb 2024 121st NickTheEASDude 🇺🇸 791 115 10ms 15 May 2024 121st dokutan 791 115 10ms 13 Aug 2024 121st maxgodfrey2004 🇨🇦 791 115 10ms 8 Jan 2025 121st Pyroan 791 115 9ms 21 Feb 2025 121st chartung17 791 115 10ms 24 Mar 2025 134th martinnorling 🇸🇪 784 116 10ms 18 Feb 2022 134th Indivicivet 784 116 10ms 9 May 2022 134th Bonjour27891 🇻🇳 784 116 10ms 15 Jul 2022 134th tri1212 🇻🇳 784 116 9ms 16 Jul 2022 134th MichalMarsalek 🇨🇿 784 116 10ms 30 Nov 2022 134th yzhs 🇩🇪 784 116 11ms 25 Jun 2023 134th Attero 🇸🇪 784 116 9ms 2 Jan 2024 134th RobertHoeh 784 116 10ms 9 Apr 2024 134th Mabeloid 🇳🇴 784 116 9ms 7 Oct 2024 134th rollershutter 784 116 9ms 24 Feb 2025 144th CedricGebistorf 778 117 10ms 19 Feb 2022 144th sjrct 778 117 10ms 5 Aug 2024 144th FranklinJiaChen 778 117 10ms 10 Aug 2024 144th Artemis21 🇬🇧 778 117 9ms 21 Dec 2024 148th Tess2662 771 118 10ms 8 Sep 2022 148th CheeseCake628 🇳🇴 771 118 10ms 20 Mar 2023 148th randolchance 771 118 9ms 20 Mar 2023 148th jeff-at-tamer-dot-codes 🇺🇸 771 118 9ms 19 May 2023 148th gabe-gallegos 771 118 9ms 19 May 2024 148th martion2007 771 118 10ms 14 Aug 2024 148th orifu 771 118 9ms 4 Nov 2024 148th TheZwierzLF 🇵🇱 771 118 10ms 27 May 2025 148th addmai 771 118 9ms 30 Jul 2025 157th RYNO8 765 119 9ms 18 Feb 2022 157th eshilo-draper 765 119 11ms 10 Oct 2022 157th georgehulme 765 119 10ms 12 Oct 2022 157th Omega65536 🇩🇪 765 119 11ms 24 Nov 2022 First Prev 81–160 of 364 Next Last